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Report information
Id: 131148
Status: new
Priority: 0/
Queue: perl5

Owner: Nobody
Requestors: mauke- <l.mai [at] web.de>
Cc:
AdminCc:

Operating System: Linux
PatchStatus: (no value)
Severity: low
Type: library
Perl Version: 5.24.1
Fixed In: (no value)



To: perlbug [...] perl.org
From: l.mai [...] web.de
Subject: B::Deparse hangs on cyclic constants
Date: Fri, 14 Apr 2017 13:06:02 +0200
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This is a bug report for perl from l.mai@web.de, generated with the help of perlbug 1.40 running under perl 5.24.1. ----------------------------------------------------------------- [Please describe your issue here] This code hangs forever: $ perl -MO=Deparse -e 'use constant FOO => do { my @x; $x[0] = \@x }; $_ = FOO' ^C Workaround: $ perl -MO=Deparse,-d -e 'use constant FOO => do { my @x; $x[0] = \@x }; $_ = FOO' use constant ("FOO", do { my @x; $x[0] = \@x }); $_ = ${my $v = [[]];$v->[0] = $v; \$v}; -e syntax OK B::Deparse dumps constants using its own function, which doesn't handle self-referential structures, so it loops forever. The -d switch tells it to use Data::Dumper instead, which is fine with cycles. Either B::Deparse needs to become smarter about cycles or -d should be on by default. 'perl -MO=Deparse' shouldn't just hang. (This issue also affects Type::Tiny (which creates self-referential objects) in combination with 'use constant' or Function::Parameters (which inlines type constraints on parameters).) [Please do not change anything below this line] ----------------------------------------------------------------- --- Flags: category=library severity=low module=B::Deparse --- Site configuration information for perl 5.24.1: Configured by mauke at Sun Feb 19 23:06:44 CET 2017. Summary of my perl5 (revision 5 version 24 subversion 1) configuration: Platform: osname=linux, osvers=4.9.6-1-arch, archname=i686-linux uname='linux simplicio 4.9.6-1-arch #1 smp preempt thu jan 26 09:41:20 cet 2017 i686 gnulinux ' config_args='' hint=recommended, useposix=true, d_sigaction=define useithreads=undef, usemultiplicity=undef use64bitint=undef, use64bitall=undef, uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='cc', ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64', optimize='-O2 -flto', cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include' ccversion='', gccversion='6.3.1 20170109', gccosandvers='' intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234, doublekind=3 d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12, longdblkind=3 ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8 alignbytes=4, prototype=define Linker and Libraries: ld='cc', ldflags ='-fstack-protector-strong -L/usr/local/lib' libpth=/usr/local/lib /usr/lib/gcc/i686-pc-linux-gnu/6.3.1/include-fixed /usr/lib /lib libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc libc=libc-2.24.so, so=so, useshrplib=false, libperl=libperl.a gnulibc_version='2.24' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E' cccdlflags='-fPIC', lddlflags='-shared -O2 -flto -L/usr/local/lib -fstack-protector-strong' --- @INC for perl 5.24.1: /home/mauke/usr/lib/perl5/site_perl/5.24.1/i686-linux /home/mauke/usr/lib/perl5/site_perl/5.24.1 /home/mauke/usr/lib/perl5/5.24.1/i686-linux /home/mauke/usr/lib/perl5/5.24.1 --- Environment for perl 5.24.1: HOME=/home/mauke LANG=en_US.UTF-8 LANGUAGE=en_US LC_COLLATE=C LC_MONETARY=de_DE.UTF-8 LC_TIME=de_DE.UTF-8 LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/home/mauke/perl5/perlbrew/bin:/home/mauke/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl PERLBREW_BASHRC_VERSION=0.73 PERLBREW_HOME=/home/mauke/.perlbrew PERLBREW_ROOT=/home/mauke/perl5/perlbrew PERL_BADLANG (unset) PERL_UNICODE=SAL SHELL=/bin/bash


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